On the Affinities of Tritylodon. 77 



Tritylodon this process is absent, or rather represented by a mere 

 rudiment. In no adult Mammal are the nares ever divided, as in 

 the Theriodonts. In the young Monotremes, however, the median 

 process of the premaxillaries is still seen, and in certain young 

 Marsupials {e.g., Macropus) there is a slight trace of it, very similar 

 to that seen in Tritylodon. So that any evidence derived from the 

 condition of the anterior nares is also in favour of Tritylodon being 

 a Mammal rather than a Theriodont. 



Taking all points into consideration, there seems to be no good 

 reason for placing Tritylodon with the Theriodonts, and many 

 reasons for leaving it where Owen placed it — -among the Mammals. 

 So far as can be made out, the ' affinities seem to be more with the 

 Monotremes than with the higher forms. It is unfortunate that 

 to-day the only living Prototherians are the extremely degenerate 

 Omithorhynchus and Echidna, but it is not improbable that the 

 Multituberculates of Jurassic and Cretaceous rocks may have been 

 Prototherians, and the presence of prefrontal bones would seem to 

 favour this view. 



ADDENDUM. 



Since the above was written I have received the following in- 

 formation from the Eev. S. S. Dornan, of Morija: — " With reference 

 to your note re specimen from Thaba-chou, I know of no locality of 

 that name, or at least of that spelling. I suspect that Thaba-tsueu 

 (pronounced Taba-tswayou) is the correct locality, but the difficulty 

 is that there are several mountains of the same name in Basutoland. 

 There is a Thaba-tsueu about three hours (18 miles) from here, a 

 prominent mountain, but I do not know whether any fossils have 

 been found there or not, though so far as I know the strata are the 

 same as here." 



It seems likely that the specimen was collected by some Free 

 Stater who took part in the Basuto war, 1879-81. 



